SECONDARY FLUORESCENCE CORRECTION FORMULAS FOR X-RAY-MICROANALYSIS .1. PARALLEL-SIDED THIN FOIL, WEDGE, AND BULK SPECIMENS

Secondary fluorescence correction formulae have been derived for speci men geometries that are commonly employed in the analytical electron m icroscope. Formulae have been derived for parallel-sided thin foil and bulk (electron probe microanalysis) specimens, for which established correction formulae currently exist, and for wedge-shaped specimens, f or which no formulae have been available to date. All derivations expl icitly account for the absorption of fluoresced X-rays leaving the spe cimen en route to the spectrometer, which the existing correction form ulae neglected wholly or in part. It is shown that the existing second ary fluorescence correction formula of Nockolds et al. for parallel-si ded thin foils, which entirely neglects the absorption of secondary X- rays, is sufficiently accurate as long as the ''sec alpha'' factor is omitted. An additional factor (y/(x + y) in Reed's notation) should be appended to the existing secondary fluorescence correction formula fo r bulk specimens in the electron probe microanalyzer to account for ne ar-surface absorption of fluoresced X-rays, which was neglected by Cas taing. The difference in the secondary fluorescence corrections calcul ated with the phi/(rho z) dependencies of Lenard (exponential) and Pac kwood and Brown (modified Gaussian) is shown to be negligible.